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By drazil, 9 years ago, In English

Hello, everyone! Codeforces Round #272 will be held at this local time. We're looking forward to your participation!

The problems are from dreamoon_love_AA and drazil(that's me) from Taiwan, and thanks 9mmlitswe for some discussion. Also we want to thank Zlobober and Gerald for helping us prepare the round, Delinur for translating the statement into Russian, and MikeMirzayanov for Codeforces and Polygon.

This is our first round on Codeforces, we hope you'll find it interesting! Please read all problem statements and discover what the main character dreamoon_love_AA do in those problems for he's really cute =)

Update1 Note this round will be held 1.5hrs earlier than usual Codeforces rounds, so please double check the starting time in your local time.

Update2 Score distribution!
Div2: 500-1500-1500-2000-2500
Div1: 500-1000-1500-2000-3000

Update3 The contests are over. Congratulations to the winners!

Div1:
1. Petr
2. qwer1561
3. kutengine
4. ifsmirnov
5. TankEngineer

Div2:
1. ridowan007
2. a00012025
3. xavier13540
4. v_Enhance
5. pkq2006

And standings are here:
Div1: standings
Div2: standings

Update4 Editorial can be found here. It's finished by now but it's welcome to tell me if anything can be improved!

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By MikeMirzayanov, 9 years ago, translation, In English

Welcome to 2014-2015 CT S02E05: Codeforces Trainings Season 2 Episode 5 - 2009-2010 ACM-ICPC, NEERC, Southern Subregional Contest. The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

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By BYN, 9 years ago, In English

In a few hours, Bayan Qualification round begins.

Qualification round will be held as our first official and required round of Bayan Programming Contest 2014-2015. It will begin on October 9th, 06:00 (UTC) for a 72-hour period, and solving only one problem is enough to advance you to the elimination round. This round is going to be an easy event with 3 very easy problems and 5 random participants will be receiving t-shirts.

Whether you are testing your luck for a random tshirt or are aiming for one of 100 tshirts of elimination round, or even if you are already planning for your trip to Tehran, you should not miss the qualification round. (contest.bayan.ir)

Please do make sure that you have fully read the main contest announcement. Lots of your questions has been already answered there.

We would like to thank MikeMirzayanov and his team specially Maxim Akhmedov (Zlobober) once again for all their efforts before and during the warm up round. Polygon was also handy and helpful for problem setting and team collaboration.

To join the stream you can follow contest's updates @bayan and you can follow the images on our Instagram page.

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By scipianus, 9 years ago, In English

Hello, Codeforces! On 6th October at 19:30 MSK the Codeforces Round 271 (Div. 2) will take place. Div1 participants can take part out of competition, as usual.

I am Ciprian Olariu (scipianus) from Romania and this is my first round on Codeforces. It is more special as it is held right after I became red on Codeforces. I would like to thank Maxim Akhmedov (Zlobober) and Gerald Agapov (Gerald) for helping me to prepare this round, Delinur for translating the statements and also MikeMirzayanov for Codeforces and Polygon platform.

In this round the main characters will be Mole and Marmot, two good friends, and you will help them in their activites.

Please note that this round will have an experimental duration of 2.5 hours and 6 problems. The scoring will be 500-1000-1500-2000-3000-3000.

I hope you will enjoy the round. Good luck and have fun :)

UPD : To avoid overlapping Topcoder SRM #635 and Bayan 2015 Contest Warm Up, we decided to move round to Monday 19:30 MSK

UPD 2 : The editorial was published here

UPD 3 : Round has finished. Thanks for participating. Congratulations to the winners:

stonebuddha

Syloviaely

vanhanh.pham

__PLEASEDONTHACKME__

LOVESY**

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By BYN, 9 years ago, In English

  • Bayan warm-up round will be held on Sunday, October 5th 2014, 13:00 (UTC) and as indicated before, it will be held on Codeforces. Warm-up round is not a required round but top 50 are going to win t-shirts and it is going to be rated for both divisions.

  • Problems have been prepared by mruxim, mR.ilchi, havaliza . We have tried our best to make the problem-set interesting and competitive and we hope you enjoy it.

  • It is necessary to have a complete profile on contest.bayan.ir before the warm-up round! And please do make sure you have selected the correct t-shirt size!

  • We have upgraded our contest platform, and we've made sure everything is stable, tuned and robust now. Thanks to all those who helped us test the unstable version!

  • The unofficial Shortcut! Round is now accessible to all, so you can check the standings and the problems.

  • Qualification round which is the first official and required round of Bayan Programming Contest 2014-2015 will begin on October 9th so don’t forget to register right now at contest.bayan.ir if you haven’t already.

  • We've created a twitter account to publish Bayan Programming Contest news. Now you can follow us @bayan.

Update 1: The scoring will be: 500 – 1000 – 1500 – 2000 – 2500 – 2500

Update 2: Warm up round is finished now. We have decided to randomly give 5 extra tshirts to 5 contestants ranked between 51 and 550. And as mentioned before, we are going to have 5 random tshirt winners in our Qualification round too.

Update 3: Congratulations to top 50, specially:

  1. fotiIe96

  2. hogloid

  3. sankear

  4. flashmt

  5. TankEngineer

Update 4: Here are 5 lucky randomly selectes tshirt winners for this round:

  1. Dongmin

  2. zxqfl

  3. shimomire

  4. arthur.nascimento

  5. SlavaSSU

Update 5: marat.snowbear has published a good editorial for this round.

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Announcement of Bayan 2015 Contest Warm Up
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By MikeMirzayanov, 9 years ago, In English

Welcome to 2014-2015 CT S02E04: Codeforces Trainings Season 2 Episode 4 (US College Rockethon 2014 + COCI 2008-5 + GCJ Finals 2008 C). The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

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By cgy4ever, 9 years ago, In English

Do you want to win a T-shirt? Do you want to learn how to design tasks for programming contest? Do you want to solve 7 tasks in 2.5 hours?

So Codeforces Round #270 is right for you. It was designed by me in California, Assembled in polygon (so Thank you MikeMirzayanov for the system and Gerald for organize and testing), will start on regular time this Sunday, don't miss it!

The organizers of Marathon24 decided to present gifts to the best finishers of the round! Best 25 participants will get Marathon24 tshirts! Thanks!


It is just an image to attract your attention. Real tshirts will be designed specially for Marathon24!

There are some articles introduced how to become a problem setter, like Problemsetter's Memoir and Way of problemsetter, but they focus on the process of contest preparation or high level thoughts. You might still don't know how to begin to write a contest: because you need to come up with ideas about problems in the first place.

In the last 3 years, I've designed lots of tasks, for example, there are 2 Codeforces Round by me (#190 and #228), and there are exactly 100 tasks designed by me on Topcoder. So I want to write a tutorial to share some specific ways to come up with new tasks.. Oh, wait, how about create a contest and write the tutorial in problem statement? So I get this idea: in each problem I will introduce a specific way of design, and I'll tell you how did I use this way to come up with a new task, and you need to solve that new task!

And this round will be a bit special: all contestants from Div1 and Div2 will compete in one contest, and it will contain all 7 problems! The duration is extended from 2 hours to 2.5 hours.

In the last, I'll do some self-introduction like marat.snowbear did in the announcement of last round. I'm Gaoyuan Chen from China, I lived in Beijing for 23 years till this August, and then I went to University of Southern California in Los Angeles to learn Game Design and Game Development. As a game designer, I'll try to make my round interesting and competitive. (And of course, there will be a problem about a popular game!) And I start to use Facebook after moved to US, so if you want to know more about me or want to chat with me, visit my facebook page: https://www.facebook.com/cgy4ever

More information like score distribution (so maybe we will have 3500p for last task!) will be announced later.

Good luck and have fun!

Update1 : score distribution: 500 — 1000 — 1500 — 2000 — 3000 — 3000 — 3500

Update2 : Contest ended. Thanks for participate! Any comment is welcome (you like the task? don't like it? it is too easy? too hard? Do you like the idea of Div1 and Div2 compete together? etc.).

Update3 : Editorial: http://codeforces.com/blog/entry/14028

Update4 : System test finished! Top 5 (in fact Top 6 because of a tie):

  1. Petr

  2. Egor

  3. riadwaw

  4. PavelKunyavskiy

  5. Jacob and rowdark

Update5 : Thank all of your support! I found I'm on the Top contributors list now. :)

Update6 : Statistics by DmitriyH: http://codeforces.com/blog/entry/14034

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Announcement of Codeforces Round 270
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By marat.snowbear, 9 years ago, In English

Hello Codeforces community! I'm happy to invite you to participate in Codeforces Round #269 for Division 2 which will be held this Friday, September 26th. As usual first division coders are invited to participate unofficially, I would appreciate a lot if they will join.

All problems are mine, so if you won't like them... well, you know whom to blame for those. I did my best in order not to disappoint you.

Since this is my first round, let me introduce myself. I'm 27, have around 7 years of programming experience and was never into ACM/ICPC and stuff like that before, learned words like "dynamic programming" couple of years ago from the algorithms course on Coursera and a bit later found this site. I'm from Saint Petersburg, Russia, was born and lived here until I became 24. Then I got married and me and my wife decided to go live somewhere else and we moved to Kyiv, Ukraine, and we love that city a lot and we will return there some day, hopefully soon.

I hope you will find my problem set interesting and varied. Meanwhile let me get you prepared for the round and introduce you the guys you will help to. So the heroes of my round are three animals from Saint Petersburg and Kyiv zoos. Those are Menshikov and Uslada ("Uslada" means Delight in Russian) — polar bears, symbols of Saint Petersburg zoo. These are my favourite animals of that zoo, they can do a moonwalk dance. Their third friend would be Khoras — an elephant from the Kyiv zoo, not sure what kind of dances he likes but he was very friendly last time we've been there. I was always fond of polar bears and elephants so now I have a round with them! Hope you will remember their names, in problem statements I call them by name and by animal type interchangeably. They want the friendship to exist between their countries and they have some minor problems you can help them with.

Traditional and untraditional regards for this round go to:

  • MikeMirzayanov and the entire team of Codeforces for the site,

  • Gerald for his help with the problems,

  • Maria Belova aka Delinur for the translation of the statements,

  • last but definitely not least, my wife Tanya for her infinite support in everything I do. This round wouldn't be here without her.

Wikipedia asked me to remind you that the day we'll have the round (at least in Russian tome zone and time zones close to it) is 269th day of the year, matches the round number perfectly thanks to Gerald's scheduling skill.

If you read up (down?) to here and I still have your attention then let me know the secret every non-red coder wants to know — in order to become red you need to solve at least 1513 problems on this site. That's a personal experience, trust me.

Another thing I'd like to mention here: gojira was cheating! In his round announcement he mentioned that he's taking the 'eldest problem setter' title from Sammarize but he didn't mention his age, so I can't tell whether this title should be mine or not. gojira, please let us know ASAP!

Will see you on the round and I will appreciate a feedback (both positive and negative) a lot!

P.S.: as usual the scoring will be announced closer to the start time, hopefully my memory won't fail and I will update this blog post then.

upd 0: small update for the English version. In English statements the names of the characters will be Menshykov, Uslada and Horace, don't get surprised :-)

upd 1: scoring will be a bit different from normal today: 500, 1000, 2000, 2000, 2500


Thanks to everybody who was with us today, hope you enjoyed it! My congratulations to the winners. worse didn't take part in today's contest so the fight was tough on both sides of the table. While Menshykov and Uslada are updating the ratings, Horace is finishing the editorial, he's promising it will be ready a bit later today.

I understood and noted some mistakes of mine in this contest, but please let me know if you have anything to tell about it. I like how it's started, thanks for beating the 5K record, that's awesome.

Unfortunately nobody solved E, though hos.lyric was very close to it. His solution failed on the second to last test, which I didn't consider to be a max test. I consider this to be my mistake that I underestimated the problem, otherwise I would leave it for some next contest.

Best regards,
Will see you at some next round,
Marat.

Round stats from DmitriyH
Editorial

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